In years gone by aquarists lit their aquariums with tungsten lights. They probably had no idea of spectrum, probably had lots of algae growth, and I would imagine the heat output would have caused problems too. Methods advance.
Nowadays there are two main lighting systems, fluorescent tubes and metal halide bulbs. Fluorescent tubes are mainly used for fish only and soft coral systems, with metal halides lighting mostly hard coral reef systems.
Aquarists have a wide choice of tubes and bulbs, with spectrum being tailored to need. One major ‘fault’ is that to achieve high power output, that is, use metal halide bulbs, there is a premium to pay for electricity. In addition, nowadays we are more aware of our carbon footprint, with all the concern about global warming that has arisen.
Well, the ‘advance’ I’m writing about is not exactly new. I’ve written about it before at some length. The lights are LED’s, which up to now (as far as I am aware) have been available in two forms – moonlight low power and full lighting high power types. It is the high power types that have ‘advanced’.
Up to now the only LED lighting available to light a reef are full arrays, where a high number of LED’s are inbuilt, with different colours incorporated. These arrays come in different sizes for different size aquariums. Trouble is, they are very expensive despite the many advantages they offer (see under Articles and under the sub-heading Equipment – ‘LED Lighting’).
The advance is not so much in technology (as far as I know) but in choice. Power LED’s are coming on to the market which offer choice in much the same way as fluorescent tubes do.
The units which, as said, resemble a fluorescent tube, are a little under 20″ (circa 51cm) in length. They each have 5 LED bulbs and can be obtained as full spectrum, natural daylight, marine white, reef white, marine blue and reef blue. I am not aware at the moment what the difference is between ’marine’ and ’reef’ in the white and the blue. Perhaps one of the blues is the actinic equivalent?
Anyway, with LED’s the aquarist can now ’mix and match’ according to need.
The big drawback, as before, is cost. I understand the light ’tubes’ individually will cost around $175. Ouch! This is tempered however by the cost of running them, which could be as low as around $15 per annum. The lights run at 12v DC. The bulbs are said to last about 50000 hours! The heat output is reported to be very low, so further savings might be made on the cost of a chiller.
The only power output indication I’ve managed to discover is that at 50cm from the aquarium, the LED ’tube’ produces around 33% more light than a 24W compact fluorescent. Fluorescents are usually much closer to the water surface than that, but at a closer point the ratios would remain the same.
I’m hoping for more information particularly on power output. I don’t know if the lights will challenge the supremacy of metal halides yet, maybe the light output close to the water surface will be something like a lower powered metal halide positioned much higher? Hmm. Maybe?
The exciting point is that the LED is still developing and slowly presenting a bigger choice to the aquarist. If the LED now, or does eventually, offer flexible lighting fully suitable to the varied needs of aquarists particularly those with reefs, then metal halides, considering the running cost and heat output, will no longer dominate. Definitely so if the LED price falls somewhat.
I feel fairly certain that in the course of time LED’s will be the light of choice, particularly for reefs, with all the advantages, especially those of running cost and lack of heat into the aquarium. Power output is the thing for the reef – that will come if it isn‘t here already.